Field of the Invention
The present invention relates to a line of sight detection device, a display method, a line of sight detection device calibration method, a spectacle lens design method, a spectacle lens selection method, a spectacle lens manufacturing method, a printed matter, a spectacle lens sales method, an optical device, a line of sight information detection method, an optical instrument design method, an optical instrument, an optical instrument selection method, and an optical instrument production method.
Description of Related Art
A design method is known which includes detecting the position of a transmission point at which a line of sight passes or passes through a lens of eyeglasses from data relating to movement of an eyeball obtained by measurement of a line of sight detection device and using this detection result in designing a spectacle lens (cf., Japanese Translation of PCT International Application Publication 2008-521027).
This conventional technology, which includes calibration on the relationship between data of movement of an eyeball (or eyeball movement data) and a transmission point, measures the movement of the eyeball as the line of sight passes through a known transmission point. Specifically, it uses an occluder made of a sheet having characteristics that is transparent to infrared used for measuring the eyeball movement data but is opaque to visible light, which is attached to the spectacle lens. This occluder is formed of a pinhole. The subject gazes an object, which is a target of gaze, through the pinhole; and the movement of the eyeball of the subject in this condition is measured to give eyeball movement data. Thus, the eyeball movement data when the line of sight passes through the known transmission point (i.e., pinhole) is measured.
This conventional line of sight detection device includes an eyeball imaging camera and obtains line of sight information such as a gaze point and a direction of line of sight based on the image of pupil obtained by the camera. Also, to further increase the precision of the line of sight information, a conventional technique irradiates infrared light to the front side of the eyeball, captures an image of the infrared light source reflected at the cornea by the eyeball imaging camera, and calculates, for instance, gaze point and direction of line of sight using the image of pupil and the image of the infrared light source reflected at the cornea.
For instance, Japanese Examined Patent Publication H06-53107 discloses a conventional line of sight detection device of the type in which the eyeball imaging camera is put on the photographed person himself. Japanese Examined Patent Publication H06-53107 discloses the construction including a goggle having a portion attached to the head of the photographed person from which portion extends a fixed portion at which the eyeball imaging camera that captures an image of pupil is attached.
This construction involves a so-called calibration state in which an image of eyeball of the subject who gazes at two to nine marks placed in front of him is captured. After the calibration is finished, it is possible to calculate which direction the subject sees based on an image of eyeball of the subject who faces in any desired direction and the image of eyeball obtained by the calibration. This enables calculation of the direction of line of sight, gaze point, and angle of rotation.
Japanese Laid-Open Patent Publication H10-66678 discloses a conventional eyeball imaging camera of the type in which the camera is not put on the photographed person himself but is of the stationary type which is placed, for instance, on a desk. Japanese Laid-Open Patent Publication H10-66678 discloses that the eyeball imaging camera, which is installed on a desk, captures an image of the eyeball of the subject. Regarding the method of calibration and calculation of the direction of line of sight in any desired direction after the calibration disclosed in Japanese Laid-Open Patent Publication H10-66678 are the same as those disclosed in Japanese Translation of PCT International Application Publication 2008-521027.
Although the technology of Japanese Laid-Open Patent Publication H10-66678 avoids need of putting the device on the subject himself, the detection of the eyeball alone fails to distinguish seeing sideward by rotating only the eyeballs from seeing sideward by rotation of the eyeballs along with rotation of the head and thus fails to calculate accurate angle of rotation and line of sight direction vector. Consequently, a camera for head is separately used to observe markers attached to the head as means for detecting the movement of the head. As described above, most of such desktop type devices need means for head detection means for detecting the movement of the head.
Upon performing such a calibration, a calibration coefficient is calculated based on information about movement of the eyeball (hereafter, eyeball movement information) of a subject who gazes at a plurality of marks the subject gazes at a plurality of marks and on the position coordinates data of the marks on an image of the forward field of view camera used for capturing the image. Then, calibration is performed using the calculated calibration coefficient so that the eyeball movement information matches with the gaze position. The calibration coefficient includes elements, for instance, error of position at which the line of sight detection device is attached to the subject and individual difference of physical form and physiological variation of the eyeball of the subject. The physical form of the eyeball includes, for instance, size of the eyeball and asphericity of cornea surface. Japanese Laid-Open Patent Publication 2000-5130 discloses a method of calculating these calibration coefficients dividedly component by component. Thus, it is difficult to completely avoid influences of the sheet on the line of sight of the subject and on the result of measurement by the line of sight detection device; some error tends to occur. The pinhole of the sheet is small, which makes the range of view narrow and unclear.